Machine Type Communication User Equipment (MTC UE) is also referred to as Machine-to-Machine (M2M) user communication equipment, and is a main application form of the current internet of things. Low power consumption and low cost are important guarantees for large-scale application thereof. The M2M equipment currently deployed on the market is mainly based on a Global System of Mobile communication (GSM) system. Recently, due to the improvement of the spectrum efficiency of Long Term Evolution (LTE)/Long Term Evolution-Advanced (LTE-A), more and more mobile operators select LTE/LTE-A as an evolution direction of a future broadband wireless communication system. M2M multi-type data services based on LTE/LTE-A will be more attractive. Only when the cost of LTE-M2M equipment is lower than that of the MTC UE of the GSM system, M2M services will be really turned from the GSM system to an LTE system.
Main alternative methods for reducing the cost of the MTC UE in the existing art includes: reducing the number of receiving antennae of the UE, reducing the baseband processing bandwidth of the UE, reducing the peak rate supported by the UE, adopting a half-duplex mode, and the like. However, cost reduction means performance reduction, and demands for cell coverage of the LTE/LTE-A system cannot be reduced. Therefore, when the MTC UE configured with a low cost is adopted, some measures need to be taken to meet coverage performance demands of LTE UE. In addition, the MTC UE is probably located at a position such as a basement and a corner, and the scenario is worse than a scenario where a common LTE UE is located. To make up coverage reduction caused by a penetration loss, some of MTC UEs need a higher performance, and therefore it is necessary to perform uplink/downlink Coverage Enhancement (CE) on some of the MTC UEs for this scenario. How to ensure the access quality of a user is a problem required to be taken into first consideration, and it is necessary to perform enhanced design on a Physical Random Access Channel (PRACH) of the LTE/LTE-A system, to ensure that the MTC UE can normally access the system.
In the LTE/LTE-A system, after sending a random access Preamble on the PRACH, the UE will receive a Random Access Response (RAR) message sent by an evolved Node B (eNB). Scheduling information of the RAR is contained in Downlink Control Information (DCI) and sent through a Physical Downlink Control Channel (PDCCH), herein the DCI further includes a 16-bit Cyclic Redundancy Check (CRC), and the CRC is scrambled by a 16-bit Random Access Radio Network Temporary Identity (RA-RNTI). The scrambling manner is as follows:ck=(bk+ak)mod 2 k=0,1, . . . , 15,
herein bk represents a (k+1)th bit in the CRC; ak represents a (k+1)th bit in the RA-RNTI; and ck represents a (k+1)th bit generated after scrambling.
The value of the RA-RNTI is determined by a PRACH occupied by the Preamble sent by the UE through the following formula:RA_RNTI=1+t_id+10*f_id,
herein t_id (0≤t_id<10) represents an index of a subframe where a first PRACH occupied by the Preamble sent by the UE is located; and f_id represents a frequency domain resource index, allocated to the UE for sending the PRACH, in the subframe indicated by t_id (arranged in an ascending order and 0≤f_id<6).
The UE receives the RAR message and obtains uplink time synchronization.